Now, in response to this post, I decided to go on PTR and test the new Faerie Fire under the premise of "With the buff to FFF's ap conversion on the PTR, will replacing a swipe with FF in your single target rotation result in higher TPS?" (For those who do not follow druids, on PTR Faerie Fire Feral Bear received an AP coefficient increase to 15%, up from 5%.)
Here are the results:
FFF's crit rate is based off spell crit
10% spell crit (I have 8.75 tooltip, plus raid buffs this is probably a low asumption)
40% melee crit (37% tooltip unbuffed)
FFF hits for 730 (without mark this is what mine was hitting for with 4865 AP, please let me know if that is an unreasonable assumption)
FFF crits at x1.5
Swipe crits at x2
FFF crits do not proc SD
Innate threat of FFF is 674
Threat in this example is 1 point of damage gives 100 points of threat (blizzard uses 2 invisible decimals for threat that do not show up in game but do on Satrina's threat mod)
Casting FF in caster form gives 3600 threat
Casting FFF in bear gives two separate threat values, the 1st one is 132289, which is the innate threat. It then applies damage and with a 731 FFF, the number jumps to 291327.
Now, (291327-132289)/207.35 (the stance modifier) = 767 - damage done = 36 which as we already discovered is the base threat of FF in caster form.
Finally, take the 132289 threat from before divided by the stance modifier gives 637.99855 or 638, added to 36, gives us 674
Now, to find the average value of FFF threat we need to take 730+674 which gives us 1404 threat. A crit is (730*1.5)+674 which gives us 1769 threat.
This gives us (1404*.9)+(1769*.1)=1440.5
In order for swipe to be more threat than FFF we set x to be the damage of swipe. x*1.5 and 2x*1.5 are the values of swipe threat for a non crit and a crit respectively.
This gives us (1.5x*.6)+(3x*.4)=.9x+1.2x=2.1x
Now, one thing I had forgotten to consider while doing this testing is that on live, the max rank of FF is actually 152 threat in caster (rank 1 on live does 36 threat in caster), as opposed to the only rank on PTR being 36. This worried me because, even thought 10% ap is much more than 116, it might not be as good as I thought it was when embarking on this process. I also began to think that the AP increase was soley for the purpose of making up for the lost threat since it is effectively a "lower rank" of the spell. Until I ran the numbers on live and discoved the base bear form threat of FF was only 480. When blizzard removed the ranks on PTR they added that extra 116 threat directly into bear form instead of keeping it on the base ability. This means that one live, the innate threat of FFF in bear is 480+152 for 632 at max rank. That is a net result of a 42 base threat increase in bear on PTR even with the reduction of the caster form threat.
Live FFF vs PTR FFF: threat increase of 42+ 10% of your ap.
Swipe must do at least 686 non crit to be worth using over a completely unbuffed FFF. While testing swipe at the same time as FF it was hitting for 394 unbuffed with 3/3 Feral Instinct.
No variable I can see could lower this number except the ammount of AP you have in bear unbuffed (correct me if I am wrong).
Raid buffs that give AP in bear (might/battle shout, HoW/SoE, UR/TSA/AM will add a minimum of 215 damage to FF), underestimating the crit of FF, and possibly overestimating the crit of swipe will all 3 only increase the number at which swipe must hit for to surpass FF.
Realistic but non mathamatically proven guess, swipe will need to be about 800 damage non crit to be more threat than FF when accounting for crit percentages.
On a non threat note, this causes you to lose the possibility to proc SD for an entire global. Use at your discretion.
Using FF on live in your rotation is not viable due to the "more powerful spell active" bug that has been in the game since LK beta and is still not fixed. Even with 5 minute FF on PTR, this bug still is around, so visit this post on the wow forumsand bump it please.
Blizzard, you finally gave us an ability to use instead of mangle, swipe, swipe on single targets, PLEASE fix the bug preventing us from using it as it is going to be an integral part of our rotation next patch.